早强免蒸养混凝土试验研究

发布时间：2018-07-28 10:28

【摘要】：近年来,随着社会发展以及城镇化水平的加深,我国人口红利逐渐消失,劳动力短缺现象愈发严重。因此,开始越来越重视建筑行业低效率高能耗的现状,总结经验,落实国情,效仿欧美发达国家,在国内逐步推行建筑工业化。装配式预制构件是建筑工业化的核心与基础,现阶段的装配式预制构件生产,仍沿用老式的预制件生产工艺,即在预制构件生产完成之后,用蒸汽养护的方法,使构件快速达到拆模强度。但是面临我国日益严峻的环境问题,蒸汽养护的方法也带来了弊端。本研究首先研制合成了一种早强型聚羧酸高效减水剂PC-Z,减水率30%~35%,该减水剂对硅酸盐水泥和硫铝酸盐水泥均具有良好适应性,且相比普通减水剂,具有明显早强效果。使用该早强型聚羧酸高效减水剂PC-Z可以在减水极限内,配制出水灰比0.32的超低水灰比混凝土,在提高混凝土强度等级的同时,早期强度也大幅度提高。随后,本研究探讨了在早强型聚羧酸高效减水剂PC-Z作用下,胶凝材料、矿物掺合料对预制混凝土免蒸养性能的影响。得到标准养护温度下最佳效果的组合为:选用5%硫铝酸盐水泥以及双掺15%矿粉、10%粉煤灰等量代替水泥,可以起到保证强度、提高和易性、节约水泥的作用。在低温条件时,矿粉和粉煤灰都会影响混凝土早强,因此选用10%~15%超细矿粉等量替代水泥,可以有效提高混凝土早期强度。最后,以山东乾元泽孚科技股份有限公司实际生产为工程实例,结合试验规律,成功研制出可以夏季(高温)、春秋季(中温)及冬季(低温)三种季节温度下,实现免蒸养的预制混凝土,可以使混凝土16 h免蒸养强度超过22.5 MPa,满足实际生产要求。最后对所研制的免蒸养混凝土进行经济性分析,计算得到本产品整体价格,要低于普通蒸汽养护混凝土。若将其成果用于实际工程的预制混凝土中,可以在不进行蒸汽养护的情况下,提高混凝土早期强度,加快模具周转,节约材料成本以及企业运营成本,并且降低能耗,减少环境污染,经济效益以及环境效益显著。
[Abstract]:In recent years, with the development of society and the deepening of urbanization, the dividend of population gradually disappears, and the shortage of labor force becomes more and more serious. Therefore, more and more attention has been paid to the current situation of low efficiency and high energy consumption in the construction industry, summing up the experience, implementing the national conditions, imitating the developed countries in Europe and America, and gradually promoting the construction industrialization in our country. Prefabricated components are the core and foundation of building industrialization. At this stage, the production of prefabricated components still follows the old-fashioned preform production process, that is, steam curing is used after the production of prefabricated components is completed. The component can quickly reach the breaking strength. However, in the face of increasingly severe environmental problems in China, steam curing methods also bring drawbacks. In this study, an early strong polycarboxylic acid superplasticizer PC-Z was first developed and synthesized. The water reducing rate of PC-Z is 30%. The water reducing agent has good adaptability to Portland cement and sulphoaluminate cement, and it has obvious early and strong effect compared with ordinary water-reducing agent. The ultra-low water-cement ratio concrete with water-cement ratio of 0.32 can be prepared by using the early-strength polycarboxylic acid superplasticizer PC-Z within the limit of water reduction. Then, the effects of cementing materials and mineral admixtures on the unsteamed properties of prefabricated concrete under the action of early strong polycarboxylic acid superplasticizer (PC-Z) were investigated. The best combination under the standard curing temperature is that 5% sulphoaluminate cement and 10% fly ash mixed with 15% mineral powder can be used to replace the cement, which can ensure the strength, improve the ease and save the cement. Under the condition of low temperature, both mineral powder and fly ash will affect the early strength of concrete, so the early strength of concrete can be effectively improved by using 10% and 15% superfine ore powder instead of cement. Finally, taking the actual production of Shandong Qianyuan Zefu Science and Technology Co., Ltd as an engineering example and combining the experimental rules, we have successfully developed three kinds of seasonal temperatures: summer (high temperature), spring and autumn (moderate temperature) and winter (low temperature). The prefabricated concrete without steaming can make the strength of the concrete more than 22.5 MPa in 16 h, which can meet the requirement of practical production. Finally, the economic analysis of the non-steam curing concrete is carried out, and the whole price of the product is calculated, which is lower than that of the ordinary steam cured concrete. If the results are applied to the precast concrete of practical engineering, the early strength of concrete can be improved, the mould turnover can be quickened, the cost of materials and the operation cost of enterprises can be saved, and the energy consumption can be reduced without steam curing. Reducing environmental pollution, economic benefits and environmental benefits are significant.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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